darguy

Hey Gang!

Long story, boring - but I finally got to race the '99 FRC again after 2 years. Bought a set of Hoosier A6's for the occasion and took 3.4 seconds off my previous best time by the end of the weekend. Qualified 6th in all 4 races, and finished 6th/5th respectively on Sunday with a DNF & DNS on Saturday. All was not lost.

So, the DNF/DNS was a result of the thermostat sticking closed and me pulling out of the first race due to coolant overtemp (had been fighting for 3rd after a first lap mele when I had to start backing off), couldn't run the second race & spent the time fixing the car. New T-stat, rad cap & coolant from the local auto parts store (thank you Lordco, for being right by the track) and I was idling at 205F for 30 min on Saturday evening and ready to go for Sunday.

Set my best time in Sunday first practice (running two run groups this weekend, for a total of 2 hrs per day track time, so no real time to cool down - me or the car). By the time the first race was half way over (was firmly in 6th at the end of a 6 car chain, big gap to 7th) I had to start backing off to manage the temp - no leaks or issues, just not enough cooling capacity. Second race I took that into consideration and had the heater cranked, and after the first couple laps where I was established firmly in 5th, I started short shifting & lifting in the corners - more concentrating on maintaining speed in the corners than top end and held my position easily to the end of the race. I've never had a cooling issue before, but I was doing 120 mph at the end of the front stretch compared to 105 with my old tires, so I guess I just hit the point where I was now making more heat and the cooling system couldn't handle it.

So, the first question: new radiator. I've got the DRM 'race' stand alone oil cooler installed and am thinking of their Ron Davis 'non-coolers T1 legal' rad. Or perhaps one from DeWitts. I like the idea of upgrading the fans, and want to wire in a switch to keep them on in the paddock.

Thoughts & comments?

ErnieN85

so here is my thought you can't beat Dewitts Ron Davis is great Too so you can't lose with either

now as to the fan Darn thing draws 30 amps so you can't leave it on long with out the engine running

froggy47

I do not know all that much I guess on cooling systems, but what would be the point of running the fans to cool the radiator coolant only (without the engine running)?

If that's what racers do?

With an elec. waterpump, I get that but that's even MORE on the batt.

Maybe you hook up aux batteries?

darguy

An electric pump would be even better, but either way I'd only run it for a few minutes to get it down to a reasonable temp to avoid heat-soaking. I've only got 20 min between track sessions sometimes and don't want it to sit that hot before running it again. The new rad will probably help considerably.

brkntrxn

Get the DeWitts radiator from Summit Racing. It is at least twice as thick as the OEM radiator and drops in place. It fixed my coolant temp issues at NASA Nats three weeks ago. I have a huge oil cooler, no AC, extra ducting, splitter, no shroud Spal fan, etc and was hitting 237 and managing 232-234. Installed the bigger DeWitts from Summit Friday night and never saw above 210 in the Saturday race and the Sunday Champ race despite running the car as hard as possible in high 90 degree air temps. Track temps were well over 100.

-Kevin

darguy

Here's a question: The car is an FRC and comes with a stock P/S cooler (air), and I have a Setrab external oil cooler. Would it make sense to get the DeWitts rad with the internal oil cooler and run the P/S through it for additional cooling? I'm thinking the rad cooler would run hotter, having the adverse effect.

Thoughts?

brkntrxn

Do you ever have issues with the PS overheating? If so, the typical fix for that is Redline fluid and a cold level barely on the stick. The fix after that is a Turn One pump.

Either way, I personally prefer to have separated systems. Makes it easier to swap a broken part at the track.

darguy

The only thing I've noticed is sluggish steering at a very tight 2nd gear uphill hairpin, and it wasn't that bad. It was a really hot day, and the car was very hot due to the cooling system issues. Probably just upgrade the fluid and deal with the rad and leave the p/s cooler as is. Thanks for the feedback!

I think I'll go with the DeWitt's rad & Spal fans. If I don't do it before the next race (it should be a lot cooler in mid Oct), I might expand the scope of the job to include diff & tranny coolers. If I remember correctly, there are kits that tie into the Z06 rear brake cooling ducts - so I'd have to install those as well!

froggy47

I would think low fluid would allow the fluid to heat up more? I know there is a bit of seepage that bothers some (out of the cap) , there are a lot of ways to fix the seepage & run correct fluid level.

brkntrxn

On a race track, your PS fluid is going to heat and expand regardless. The lower cold fill level allows the expansion to NOT spew out of the cap, onto your headers, your tires, and your windshield when you are battling for the lead at 140mph.

brkntrxn

OP,

I have the 16" Spal fan and feel I could have gone with the 14" just as effectively.


-Kevin

RS-08C6Z51

Sent you a PM also but thought info would be helpful to others.

What were your peak oils temps during race? What are the dimensions of your oil cooler and is it in front or behind radiator? I've seen some C5's at NASA events with the oil cooler behind the radiator. Wouldn't think it would help much with super heated air from the rad going through it but would help coolant temps not having it in front of the rad.

Thanks.

brkntrxn

Rob,

As for the oil cooler, I will need to take some measurements, but it is MUCH larger than most. PCM of NC used my car as a prototype and they can sell you the kit if you want them to bundle one together for you.

We went with the oil cooler in front of the radiator for ease of packaging. There is more room in front than behind and it makes for an easier, universal mounting approach with the brackets. The other reason is oil temps are usually more critical than coolant temps. Meaning, oil temps are the first thing to start rising before you start having coolant temps... In the experiences of most of us.

Before the oil cooler, I could hit 307* oil temps in two laps while coolant temps stayed lower for longer. After the oil cooler, my oil temps stay in the 230-250 range depending on time of year. They are stable enough that I never monitor them anymore, I only watch coolant temps. At some point, I need to put gauges for each in the car.

On the question of combined systems or not, I am a proponent of separated systems for reliability and each of changing. I have had to change radiators at the track due to track debris and if I had combined systems it would have been messier and more complicated. Keeping them separated is just another assurance in reliability for me in that damage to one cooler does not affect two cooling systems.


-Kevin

RS-08C6Z51

Great info. Thanks Kevin!

froggy47

OK, makes sense, the stock resevoir and dip stick marks are basically out of spec for a track car.

I have seen on a friends G8 supercharged car a custom res/cap from some Aussie race parts company (IIRC). Drops in on an LS motor.

Maybe something there to check out.

96GS#007

If it's permissible for your class, you might consider a different hood. I know a couple guys that are supercharged and swapping to a vented hood did the trick regarding the various temps since much more air will flow through the radiator and engine compartment.

darguy

Thanks for all the good info, Kevin. I don't have my notes in front of me, but I had the same experience with the oil temps - way too high, put in the oil cooler and it's so stable now that I use the DIC to monitor the coolant temp instead. I like the simplicity of every system being discrete as well.

What do you mean by a "no shroud Spal fan"? I was thinking of using the setup from DeWitts: -> link

We completely re-designed our C5 fan package to utilize a lazer cut aluminum shroud. The shroud incorporates (4) four rubber flapper valves to improve air flow at high speeds and close at slower speeds. Two Spal 12" high performance fan provide 3200 cfm, which doubles the factory output.

Thoughts?

I'm in Improved Production 1, a lot like Improved Touring but with more latitude on upgrades to the brakes - I don't believe I can change the bodywork. I'll check though, in case the new rad & fans doesn't quite do the trick.

blkbrd69

Kevin;

Would love to see photos and get size of the oil cooler you had done to get those great results.

I have this tread about oil coolers if you would like to post them there.

If you dont want to post them, PM me for email.

https://www.corvetteforum.com/forums...iscussion.html

Thank you.

brkntrxn

If this is not a 100% street car with AC and whatnot, you don't need a shroud. A shroud funnels air through the radiator and though the fan when the fan is running while you are idling or barely moving. AT SPEED, the fans turn off at 35mph and now the shroud becomes a blockage to free air flow through the radiator. Anything other than a bare fan is going to block air flow while on track.

I went with a single Spal 16" pull fan mounted to the back of the radiator and wired into the OEM harness. After seeing how much air it pulls and verifying that it keeps my coolant dead on the thermostat setting at idle, I am certain a smaller 14" would do just fine.

darguy

Thanks! The car is 100% race car, trailered to the track. Used to be my daily driver, but that was a while ago now... I'll be getting rid of that fan shroud, I guess! How did you mount the Spal fan, some kind of bracket that attaches to the back of the rad? Do you have a switch to keep it on for a while in the paddock after shut-down, or is it cool enough that you don't have to worry about it?

Really appreciate your input!